Defeat of Japanese soldiers after the banzai charge in the Battle of Attu, May 29, 1943.

A Banzai charge is the term used by the Allied forces to refer to Japanese human wave attacks mounted by infantry units. This term came from the Japanese cry "Tenno Heika Banzai" (天皇陛下萬歲?, "Long live the Emperor"), shortened to banzai, specifically referring to a tactic used by Japanese soldiers during the Pacific War. Banzai charges had some successes at the ends of battles by overcoming soldiers unprepared for such attacks.

The Banzai charge is considered to be one method of gyokusai(玉砕?, "jade shards"; honorable suicide), a suicide attack, or suicide before being captured by the enemy such as seppuku. The origin of the term is a classical Chinese phrase in the 7th-century Book of Northern Qi, which states "大丈夫寧可玉砕何能瓦全", "A man would rather be a shattered jade than be a complete roof tile". In Japan, since the Sengoku period, samurai followed the code called bushido, defining behaviors loyal and honorable. Among the rules there existed a code of honor that was later used by Japanese military governments.

With the revolutionary change in the Meiji Restoration and frequent wars against China and Russia, the militarist government of Japan adopted the concepts of Bushido to condition the country's population to be ideologically obedient to the emperor. Impressed with how samurai were trained to commit suicide when a great humiliation was about to befall them, the government educated troops that it was a greater humiliation to surrender to the enemy than to die. The suicide of Saigo Takamori, the leader of old samurai during the Meiji Restoration, also inspired the nation to idealize and romanticize death in battle and to consider suicide an honorable final action.

During the war period, the Japanese militarist government began disseminating propaganda that romanticized suicide attack, using one of the virtues of Bushido as the basis for the campaign. The Japanese government presented war as purifying, with death defined as a duty.[citation needed] By the end of 1944, the government announced the last protocol, unofficially named ichioku gyokusai(一億玉砕?, literally "100 million shattered jewels"), for the purpose of resisting opposition forces until August, 1945.

During the invasion of China banzai charges were reported to have worked extremely well, because the Chinese troops were poorly educated and undisciplined, breaking at the horrifying sight of massed blades. Conversely, in most battles against American soldiers, the charges were generally halted by superior firepower.

During the U.S. raid on Makin island, on August 17, 1942, the U.S. Marine Raiders attacking the island initially spotted and then killed Japanese machine gunners. The Japanese defenders then launched a banzai attack with rifles and swords but were stopped by superior American firepower from M1 Garand rifles, Thompsons, and BARs that left dozens of Japanese dead. The pattern was repeated in additional attacks, but with similar results.[1]

During the Battle of Guadalcanal, on 21 August 1942, Colonel Kiyonao Ichiki led 800 soldiers to launch a direct attack against the American line guarding Henderson Field in the Battle of the Tenaru. After small-scale combat engagement in the jungle, Ichiki's army launched its banzai charge on the enemy; however, with an organized American defense line already in place, most of the Japanese soldiers were killed and Ichiki subsequently committed suicide.[2]

The largest Banzai attack of the war took place in the Battle of Saipan in 1944 where, at the cost of almost 4,300 dead Japanese soldiers, it almost destroyed the 1st and 2nd Battalions of the 105th U.S. Infantry, who lost almost 650 men.[3]

Banzai charges most often took place by remnants of groups of surviving troops following defeats in organized battle, as a last resort and alternative to surrender.